"That looks like line noise" "What's line noise?"

One way to know you're old: you tell someone that a certain programming
language "looks like line noise", and their reply is: "line noise?" ...

So, for those who also have no idea, let's fire up the wayback machine.

For me, line noise comes from the days of using a modem. No doubt there
were people suffering from it before that on hard-wired serial lines,
but that's before my time. I first encountered it with my trusty
Commodore 1670 modem plugged into a VIC-20. It would just turn bits
into audio and vice-versa, and that meant dealing with whatever would
come down the wire.

Our original phone line had this strange device in line which allowed
our security system to seize it in the event it needed to dial out.
The way they wired it, this meant there was a long run all the way from
our demarc to the security system, into that jack (RJ31X?), and then
back to the demarc. There, it met up with the original 1960s house
wiring and went on to all of the inside jacks.

This particular wire ran through a hollow space just off a hallway where
our house's air return was, and it punched through a wall into the hall
closet where our security system's brain lived. All of this so far
is no big deal. It's a typical set up all over the country. The
problem is that some knucklehead stapled through the wire
inside that air return.

That meant any time our A/C or heat was on, the air flow would perturb
the wire, and it would wiggle against that staple, and it would generate
audible noise on the line. For whatever reason, that noise tended to
just be on our side of things. People on the other end never heard it
while talking to us.

Back to the topic at hand, this also created line noise which I would
see while connected to some BBS was entirely on my end. I might start
typing out a sentence and would be presented with some funky characters
in the middle. Now I had a decision to make: did that character make
it to the BBS and echo back to me, in which case I should backspace
over it, or was it just on my end, in which case I should ignore it?

More often than not, I wound up deleting the whole line and starting
over, hoping to make it through before another burst of noise dropped
some wacky character on my screen. For some reason, there were some
which appeared more than others. The radical symbol up in the upper
reaches of code page 437 (the so-called "high ASCII") was a
particularly common offender in my house when using my PC later on.

It was a good couple of years until I picked up a modem which would do
MNP or V.42/LAPM error correction. After that, those funny characters
went away and life moved on. All of our CRCs and other ways of dealing
with errors now make life pretty nice by comparison.